Peel and finely grate the beetroot. Stir butter until creamy. Mix in the eggs one after the other, alternating with 1 tbsp. flour. Mix remaining flour, baking powder and salt and stir in briefly together with buttermilk and beetroot.
Preheat the waffle iron for rectangular waffles (double waffle 15 x 18 cm) well and spread a thin layer of oil on it. Pour in approx. 2 tbsp. of dough per side and bake for 3-5 minutes. Bake another 3 double wafers one after the other.
Crumble the feta. Chop the nuts. Quarter the double wafers, arrange and sprinkle with feta and nuts. Serve with liquid honey and chilli flakes.